Polish-Japanese Institute of Information TechnologyElectronic laboratory

EL-Exp. 6 OPERATIONAL AMPLIFIER AND NEGATIVE FEEDBACK

Polish-Japanese Institute of Information Technology Electronic laboratory

Experiment

6 OPERATIONAL AMPLIFIER AND NEGATIVE FEEDBACK Academic year

Names Marks Date

Supervisor ...

6.2. EXPERIMENTAL PART

6.2.1. Observation of the output signal of the operational amplifier with the feedback loop open

Output voltage: ……….

Comment: ………..

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6.2.2. Observation of the output signal of the operational amplifier with the feedback loop closed

Output voltage: ……….

Comment: …..………..

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1

Configuration of the opamp selected in sec. 6.2.2. a)

EL-Exp. 6 OPERATIONAL AMPLIFIER AND NEGATIVE FEEDBACK 6.2.3. Measurement of amplifier parameters in inverting configuration

6.2.3.l. Measurement of the DC gain

a) Comment on loading effect: ……….

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b) Measured voltages:

- at the amplifier input V we : ………..

- at the virtual ground node V we(-) : ………..

- at the amplifier output V wy : ………..

c) Real value of the voltage gain | k v | = |V wy |/V we = ………..

Comment: ………..

………

………

d) Measured R 1 = …………..

e) Input resistance of the amplifier R we :

I we = (V we - V we(-) )/R 1 = ……….

R we = ……….

Comment: ………..

………

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6.2.3.2. Measurement of the amplitude characteristic

V WE1kHz = ……… k v = V WY /V WE

f kHz 0.1 0.2 0.4 0.7 1 2 4 7 10 20 40 70 100 200 k v V/V

k v dB

2

Calculation of R

:

R 2 =

EL-Exp. 6 OPERATIONAL AMPLIFIER AND NEGATIVE FEEDBACK

fu -3dB = ... (from graph), f u-3dB = ... (direct, from the display)

6.2.3.3. Measurement of the maximum speed of the output voltage change

Input signal data:

Amplitude ……….. Vpp, frequency ………... kHz Leading edge speed: ……….. V/s Trailing edge speed: ………... V/s

6.2.4. Measurement of the noninverting voltage amplifier parameters

6.2.4.l. Measurement of the DC gain

b) Measured voltages:

- at the amplifier input V we : ………..

- at the virtual ground node V we(+) : ………..

- at the amplifier output V wy : ………..

c) Real value of the voltage gain | k v | = |V wy |/V we = ………..

d) Measured R 3 = …………..

e) Input resistance of the amplifier R we :

3

Saturated amplifier response

EL-Exp. 6 OPERATIONAL AMPLIFIER AND NEGATIVE FEEDBACK

I we = I we = (V we - V we(+) )/R 3 - V we(+) /10 ⁷ = ……….

R we = ……….

Comment: ………..

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f) Comment on opamp bias current effect: ………

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4